I’m still working on the summary of our third forages class, but I wanted to share some (hopefully) good news about Himalayan Blackberries. Anyone who lives in Oregon is probably wondering how there could be good news about this species. For everyone else, here’s a quick summary of our local blackberries:
- Rubus ursinus (Trailing Blackberry) – A native species to western North America. It has thin stems that can grow up to 20 feet. This species has been used in the breeding of several commercial berry crops including marionberry (a blackberry cultivar), and loganberry and boysenberry (raspberry hybrids). I do not have a picture of this variety, as it is has been largely supplanted by the exotics.
- Rubus laciniatus (Evergreen Blackberry) – An exotic invasive blackberry species from Europe. It spreads rapidly, but can be controlled by repeated mowing. I’ve seen this species on our property, but couldn’t find a specimen to photograph today. It’s easily identified by the deeply incised leaves which remain green over the winter.
- Rubus armeniacus (Himalayan Blackberry) – An exotic and extremely invasive blackberry species from Asia. The stems grow up to 30 feet in length in only two years. They are constantly replaced by new growth, with the dead old stems forming a progressively thicker wall of thorns. Himalayan Blackberries are resistant to many pesticides and occasionally swallow up tractors (those that have been parked for too many years). A 10 foot wall of blackberries looks like this:
Where’s the good news?
Well, in 2005 blackberry rust was discovered in Oregon. This is a fungal disease which is has been used in other countries to control invasive varieties of blackberry. The disease creates bright yellow spots on the bottom of the leaves, which eventually bloom into shades of orange and red. The leaves turn brown and die, and many of the plants are killed or severely weakened. (You can find pictures here.) The state had been investigating this fungus as a biological control well before it was discovered here, but they were being understandably cautious given how many other imported “problem solvers” tend to go awry. In this case, the disease seems to only affect the exotic blackberry varieties and the cultivated “thornless” blackberry.
We heard about the rust in the forages class (the instructor was apparently briefly accused of importing it), and the response from almost everyone was “Where can I get some?” It’s really only a matter of time, as most western counties in Oregon now report cases of the rust, and the spores are carried on the wind. As with any biological control, you have to wonder if there will be unintended consequences, but so far it seems like a great measure to restore balance to many native habitats. More details are available here and here.